Gram's stain

Gram's stain
Gram's stain or Gram stain 'gram- n
1) a method for the differential staining of bacteria that involves fixing the bacterial cells to a slide and staining usu. with the basic dye crystal violet, treating with an iodine solution to fix the dye, washing with acetone or alcohol to decolorize the dye, and counterstaining usu. with a red safranine dye which shows up only if the crystal violet has been decolorized, that results in gram-positive bacteria retaining the purple dye and gram-negative organisms having it decolorized so that the red counterstain shows up, and that is believed to depended on differences in the structure and composition of the bacterial cell walls which facilitate or prevent the decolorization of the crystal violet dye by the alcohol or acetone called also Gram's method
2) the chemicals used in Gram's stain

* * *

a method of staining bacterial cells, used as a primary means of identification. A film of bacteria spread onto a glass slide is dried and heat-fixed, stained with a violet dye, treated with decolourizer (e.g. alcohol), and then counterstained with red dye. Gram-negative bacteria lose the initial stain but take up the counterstain, so that they appear red microscopically. Gram-positive bacteria retain the initial stain, appearing violet microscopically. These staining differences are based on variations in the structure of the cell wall in the two groups.
H. C. J. Gram (1853-1938), Danish physician

Medical dictionary. 2011.

Игры ⚽ Поможем сделать НИР

Look at other dictionaries:

  • Gram's stain — noun a staining technique used to classify bacteria; bacteria are stained with gentian violet and then treated with Gram s solution; after being decolorized with alcohol and treated with safranine and washed in water, those that retain the… …   Useful english dictionary

  • Gram's stain — or Gram stain noun Etymology: Hans C. J. Gram died 1938 Danish physician Date: 1903 1. a method for the differential staining of bacteria by treatment with a watery solution of iodine and the iodide of potassium after staining with a… …   New Collegiate Dictionary

  • Gram's stain — a method of staining bacterial cells, used as a primary means of identification. A film of bacteria spread onto a glass slide is dried and heat fixed, stained with a violet dye, treated with decolourizer (e.g. alcohol), and then counterstained… …   The new mediacal dictionary

  • Gram method stain solution — (gram) [Hans Christian Joachim Gram, Danish physician, 1853–1938] see Stains and Staining Methods, under stain, and see gram negative and gram positive …   Medical dictionary

  • Gram-positive — bacteria retain the color of the crystal violet stain in the Gram stain. This is characteristic of bacteria that have a cell wall composed of a thick layer of a particular substance (called peptidologlycan). The Gram positive bacteria include… …   Medical dictionary

  • Gram-negative — bacteria lose the crystal violet stain (and take the color of the red counterstain) in Gram s method of staining. This is characteristic of bacteria that have a cell wall composed of a thin layer of a particular substance (called peptidoglycan).… …   Medical dictionary

  • gram-variable — gram vari·able gram ver ē ə bəl, var adj staining irregularly or inconsistently by Gram s stain * * * gram var·i·a·ble (gram varґe ə bəl) appearing to be a mixture of gram positive and gram negative organisms, said of gram positive… …   Medical dictionary

  • Gram-variable — /gram vair ee euh beuhl/, adj. (often l.c.) of or pertaining to bacteria that stain irregularly with Gram s stain, being neither Gram positive nor Gram negative. [1955 60; see GRAM S METHOD] * * * …   Universalium

  • Gram's solution — gramz n a watery solution of iodine and the iodide of potassium used in staining bacteria by Gram s stain Gram gräm Hans Christian Joachim (1853 1938) Danish physician. Gram introduced his method for the differential staining of bacteria in 1884 …   Medical dictionary

  • Окрашивание По Граму (Gram'S Stain) — метод окрашивания бактериальных клеток, применяемый для их первичной идентификации. Тонкий слой, содержащий бактерии; наносится на предметное стекло, высушивается и фиксируется воздействием тепла; затем окрашивается фиолетовым красителем,… …   Медицинские термины

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”